High-speed alpha-numeric printer



July 18, 1967 G. T. MORGAN 3,331,299

HIGH-SPEED ALPHA-NUMERIC PRINTER Filed Feb. 1, 1965 INVENTOR. 5F4/1/7 7440904 wi wa United States Patent 3,331 299 HIGH-SPEED ALPHA-NUMERIC PER Grant T. Morgan, Arcadia, Califi, assignor to Consolidated Electrodynamics Corporation, Pasadena, Calif-, a corporation of California Filed Feb. 4, 1965, Ser. No. 430,326 Claims. (Cl. 95-45) ABSTRACT OF THE DISCLOSURE A high speed printer utilizing a photosensitive printing medium for recording alpha-numeric characters a line at a time. The printer utilizes a bank of mirror galvanometers each of which is adapted to direct light from a source toward a selected character in a character generating element which is interposed in an optical system between the bank of galvanometers and the printing medium. Subsequent to the correct angular positioning of each of the galvanometer mirrors corresponding to the desired arrangement of characters in the line, light fom the source is reflected from the mirrors to the selected characters and onto the medium to record all charactes in the line simultaneously.

This invention relates to read-out devices and, in particular, to a photographic system for printing alpha-numeric characters at high speed.

One of the fastest developing areas of todays technology is the field of data processing. The result has been a steady stream of improvements with special emphasis on the heart of a data system, the computer. So substantial-have these improvements been that they are now threatening to outstrip the capability of the supporting equipment which together with the computer go to make up a data processing system. An example of one component of supporting equipment where this is true is the printer or read-out device associated with the system. Since the printer is normally a mechanical device, it is characterized by relatively high inertia and a correspondingly slow speed of operation. With the increase in speed of the other components of a data processing system, the printer has become one of the limiting factors in the over-all speed of these systems. Since the value of computer time has increased substantially, it has become imperative that the speed of the read-out component as well as other supporting components be increased in order to put the entire system on a more eflicient, economical basis.

To this end, intensive efforts have been made. As a result, printer design has become highly refined and sophisticated. But it is, nevertheless, still conventional to require type bars, keys, etc. and still faced with the inevitable inertia limitations of a mechanical system. To achieve improvements on the order of magnitudes, it has become apparent that new basic design concepts must be explored if the speed of this component is to more nearly approach the over-all speed of the average data processing system.

Among several basic system approaches that have been advocated has been the use of a photographic system in which some type of electronic or mechanical shutter is substituted for the heavier type bar, keys, etc. of conventional printers. The use of galvanometers and a supporting optical system in order to achieve high-speed printing of alpha-numeric characters is an example of such a mechanical shutter. A number of systems have been proposed in which galvanometers are employed since such devices lend themselves extremely well to this particular application because of their inherently low inertia. However, systems heretofore used have required the use of two or more galvanometers in tandem. Such systems are sublect t0 e d advantages that means for providing a coordinated drive of the several galvanometers is required and substantial difliculties in printing certain letters as, for example, W are encountered.

In contrast, the present invention provides a galvanometer system in which only a single galvanometer is needed to print each character. More particularly, the invention is an eletcro-optical system for recording informationbearing characters. The invention comprises a light-sensitive recording medium, a plurality of galvanometermounted reflectors, a character-generating element defining a plurality of information-bearing characters interposed in the system between the reflectors and the recording medium, and a light source. Means for deflecting the reflectors to predetermined positions are also provided whereby light from the source is directed at the element characters and the medium in a predetermined sequence according to positioning of the various reflectors.

An added advantage of this system is that is can be readily aded to existing oscillographs and oscillograph recording systems for providing trace identification, timing indications, etc. When used in a high-speed printer for data processing systems, an entirely new camera design is more desirable since a printer for use with a computer system would require more channels and paper capacity than is available in existing oscillographs. An alpha-numeric printer as contemplated by the present invention is possessed of other significant advantages, especially when adapted to a data processing application. These advantages include higher printing speed resulting in quick data access and cost savings in computer time, lower initial costs, higher reliability, lower noise levels, and compactness.

These and other advantages of the invention will be more fully understood by reference to the following figures in which:

FIG. 1 is one embodiment of the character-generating element defining the alpha-numeric characters to be recorded; and

FIG. 2 is a schematic representation of one orientation of the system contemplated by this invention.

The system as depicted in FIGS. 1 and 2 and as described herein illustrates one embodiment of the invention. In this embodiment the character-generating element is an opaque mask provided with a plurality of translucent apertures defining each of the possible characters to be recorded. Light from the source is directed through the particular characters to be recorded and ultimately reaches the recording medium where the character is imaged.

'One alternative to using a mask with translucent characters is to provide a character-generating element comprising a support upon which is mounted a plurality of reflectors, the reflectors defining the possible characters to be recorded. Light from the source is then reflected rather than transmitted toward a recording medium by the element characters. Such an alternate embodiment lends itself to compact packaging since the reflective characters provide a convenient means for folding the optics of the system.

A mask 3 as depicted in FIG. 1 is provided with the characters 5- of the English alphabet and the digits 7 of the Arabic numeral system. Symbols and characters other than letters and numbers are easily provided in substitution for or in addition to those shown in FIG. 1. Light reflected by the various galvanometers is passed through the mask characters and imaged on the medium where the line of characters is to be recorded.

The dimensions and design of the mask are governed by several factors. Primary among these is the angular sweep or field of the individual galvanometers. Since the field of a galvanometer is limited to a certain maximum angle, the length of the mask cannot exceed this di mension. In addition, a certain minimum spacing must be maintained between letters in order to take into account inaccuracies and nonlinearities in the operation of this system. Provision of this separation prevents errors due to possible overlapping or inaccurate positioning of the galvanometer-reflected light beam relative to the particular character to be recorded. The location of the mask relative to the remainder of the system with which it is employed is described in more detail in conjunction with the description of FIG. 2.

The various elements of the system of FIG. 2 are as follows. A light source 2 is located to one side of the field defined by a bank of galvanometers 8 and a recording medium 22. Light from the source is directed through a condensing lens 4 to a mirror 6 and is reflected toward the bank of galvanometers 8. The galvanometer bank comprises a magnetic block 10 in which a plurality of galvanometers 12 are mounted. The galvanometer block 10 is a permanent magnet with poles located on opposite sides of the galvanometer case and is provided with a number of slots adapted to engage magnetically permeable pole pieces mounted externally on the galvanometer casing. These pole pieces also extend through the galvanometer casing into its interior to define a very narrow gap in which the galvanometer coil is suspended. The number of galvanometers 12 mounted on the magnetic block correspond to the total number of characters and numerals com-prising one line. Each galvanometer illuminates one of the selection of characters in the mask during the recording of each line. It is possible, however, to image the same character as, for example, a vowel, at more than one place in each line by the mechanism of deflecting each of the galvanometers corresponding to those line positions so that the light from each is passed through that particular character.

A number of lenses are located in the optical path between the recording medium and the galvanometers. The

first is a lens 11 which forms a part of the lens assembly upon which the character mask is mounted. Lens 11 is a section of a spherical lens. When necessary, the effect of lens 11 can be augmented by the addition of one or more similar lenses. Lens 15, located preceding lens 11, illustrates this function. The function of these lens(es) is to image the line of galvanometers at the recording medium. An opaque mask 14, such as is illustrated in more detail in FIG. 1, containing the various possible characters desired for the read-out in the form of translucent windows is provided adjacent lenses 11 and 15.

Located adjacent the mask on the side opposite lenses 11 and 15 is a first spherical lens array 17. Arranged between this first spherical lens array and the recording medium is a second array of spherical lenses 18. The purpose of the second array is to provide magnification of character images relative to their size in the mask. The first array coacts with the second to accomplish'this result. Both of the sperical lens arrays are preferably fabricated from molded plastic. Molded plastic is use-d because it has been found to be the most practical material in view of the relatively small size of each of the arrays.

Continuing along the optical path, a mirror 20 is provided for reflecting light passing through the character mask from the optical axis tothe recording medium as shown in FIG. 2. The recording medium is a photosensitive paper such as that used in conventional oscillographs. The entire system including the magnetic block is mounted in a light-tight enclosure (not shown).

In operation, the system performs in the following manner. A line of information to be recorded is presented in the form of electrical signals which are transmitted to the individal galvanometers to position the galvanometer mirrors such that they reflect light from the source through the proper characters in the mask and onto the recording medium. The electrical circuitry for generating the positioning signals can be of several designs and,

hence, a specific design is not an essential part of the printer of this invention. One form which such circuitry can take is a combination of power supply, voltage divider network and logic circuit. With such circuitry, the output of the power supply is broken down by the divider into as many individual voltages as there are possible characters. The voltages corresponding to the particular characters to be recorded are then connected and transmitted by the logic circuit to the proper galvanometer for correct positioning of the mirror relative to character which it will record. A more detailed description of the electrical circuitry associated with typical galvanometer systems can be found in the manual published by Consolidated Electrodynamics Corporation of Pasadena, Calif. This manual is: Galvanometer Users Handbook, Bulletin No. 7300A, June 1963.

One the proper deflection has been set on the galvanometers, the light source is pulsed. Light from the source passes through condensing lens 4 and is reflected toward the bank of galvanometers. As indicated previously, there are as many galvanometers provided in the block as there are total characters in a line to be recorded. Typical systems have a capacity of approximately 50 characters per line. The light reflected from mirror 6 onto the galvanometer mirrors is broken into incremental segments by these mirrors with each segment being directed generally down the optical axis of the system toward lenses 11 and 15 and, in particular, toward the character to be illuminated. The light segments are directed through the characters in the mask and the first spherical lens array 17 located adjacent the mask. As previously indicated, lenses 11 and 15 are arranged such that the line of galvanometer mirrors is imaged on the recording medium. This means that regardless of the direction in which light from the source is reflected by the galvanometer mirrors, it arrives at the paper at the point opposite the galvanometer which reflected it. Thus, the direction that the light takes by virtue of galvanometer deflection will determine the character to be printed while the location of the galvanometer in the magnetic block in relation to the other galvanometers determines the position of this character relative to all others in the line imaged on the recording medium.

After the light from the source passes through the particular characters in the mask, it continues along the optical path toward and through the second spherical lens array 18. As indicated, this array of lenses provides some magnification of the character image on the record with respect to the character size at the mask. Due to the optics of the system, each of the lenses in array 18 images more than one character on the mask, i.e., each lens images a section of the mask. Therefore, any magnification action by these lenses will also magnify the space between characters as seen on the mask. Absent the provision of some means to prevent it, the resultant character spacing on the record for these conditions is larger than is desired. For this reason, the first array of spherical lenses 17 is interposed in the system adjacent the mask and between it and spherical lens assembly 18. These lenses magnify individually the objects seen by the spherical lenses 18 and thereby reduce the spacing-to-character ratio on the paper relative to the same ratio in the mask. The mangification action by these lenses also makes possible :a reduction in total mask size. Since lenses assembly 17 also images the galvanometer mirrors at the spherical lens assembly 18, the possibility of spill-over at these lenses is reduced.

Light passing from array 18 then strikes mirror 20 where it is reflected to the medium 22 and recorded therein. The medium 22 is photosensitive and preferably a paper of the direct-printtype for yielding a visible re cording nearly instantaneous with the recording event.

In addition to its utility in the data processing field, the system of this invention can also be applied in the following areas: (1) as a trace numbering mechanism when commutating channels in an oscillograph; (2) as a real time-analog recorder; (3) as a counter-printer; and (4) in teletype applications.

What is claimed is:

1. An apparatus for recording characters and symbols comprising a photosensitive recording medium, a l1ght source, a plurality of DArsonval galvanometers, each of the plurality of galvanometers supporting a mirror for reflecting light from the source in a predetermined direction, and optical system for collecting and reflecting light from the source to the galvanometers, a character-generating element including a plurality of translucent apertures defining the characters and symbols to be recorded, means connected to each galvanometer for producing deflection of the mirrors from a rest position and an optical system interposed between the plurality of galvanometers and the element and between the element and the medium for imaging the characters to be recorded on the medium in accordance with the deflections of each of the pluralityof galvanometers. I

2. A high-speed alpha-numeric printer comprising a character-generating mask including a plurality of alphanumeric characters to be recorded, a source of photosensitive direct-print paper, a plurality of galvanometers including suspensions upon which reflectors are mounted, a magnetic block for mounting the galvanometers, means connected to the galvanometers for passing a current of a predetermined amplitude through each galvanometer suspension, energization of the suspension producing deflection of the reflector proportional to the amplitude of the input signal, a light source located outside the planes defined by the ends of the magnetic block and the recording medium, means for momentarily energizing the light source, a condensing lens and a mirror interposed in an optical path between the light source and the bank of galvanometers for focussing and reflecting light emitted from the source to the deflected galvanometer mlrrors, a lens adjacent the element for imaging the galvanometer reflectors on the paper, a first spherical lens array located in the optical path between the element and the directprint paper, a second spherical lens array located in the optical path between the first spherical lens array and the direct-print paper, and a mirror located in the optical path between the second spherical lens array and the direct-print paper for reflecting the character imaged thereon to the paper.

3. An electro-optical system for recording a line of characters comprising:

a light-sensitive recording medium having a predetermined character per line capacity;

a light source;

a plurality of galvanometer-mounted reflectors, the

number of reflectors corresponding to the total number of characters in the line to be recorded;

a character-generating element defining a plurality of information-bearing characters interposed in the systorn between the reflectors and the recording medium; and

means for deflecting each of the reflectors to a predetermined position to select a character to be recorded from the element whereby light from the source is directed from the reflectors to the element and onto the recording medium according to the positioning of the reflectors to print all of the characters in the line to be recorded simultaneously.

4. An electro-optical system for simultaneously re cording a line of at least two characters comprising:

a light-sensitive recording medium;

a light source;

a combination of lenses and mirrors interposed between the light source and the recording medium for gathering and reflecting light from the source through the system to the recording medium;

a plurality of galvanometer-mounted reflectors, the

number of reflectors corresponding to the total number of characters to be recorded in the line;

a character-generating element defining a plurality of alpha-numeric characters, the element being interposed in the optical system between the reflectors and the recording medium;

means for deflecting each of the deflectors to a predetermined position to select the character to be re corded by that reflector from the element; and

means for transmitting light from the light source responsive to the positioning of the reflectors whereby light from the source is directed from the reflectors to the character generating element and onto the recording medium according to the positioning of the reflectors to record all of the characters in the line simultaneously.

5. An electro-optical system for recording a line of information, a line at a time, comprising:

a light-sensitive recording medium;

a light source;

a combination of lenses and mirrors defining an optical system between the light source and the recording medium for gathering and reflecting light from the source through the system to the medium;

a plurality of galvanometer-mounted reflectors, the

number of reflectors corresponding to the total number of characters to be recorded in the line;

a magnet block for mounting the reflectors in side by side relationship;

a character-generating element defining a plurality of information-bearing characters to be recorded interposed in the optical path between the light source and the recording medium, the selection of characters in the element being arranged in side by side relationship;

means for deflecting each reflector to establish an optical path between the source and the character to be recorded by the reflector; and

means for pulsing the source responsive to positioning of the reflectors whereby light from the source is directed at the selected characters and onto the recording medium in a predetermined pattern according to positioning of the reflectors and records each character in the line simultaneously for each pulsing of the light source.

6. An apparatus for recording alpha-numeric characters comprising:

a photosensitive recording paper;

a light source;

a lens and mirror system defining an optical path between the source and recording paper;

an elongated magnet block;

a plurality of DArsonval galvanometers adapted to be mounted in the magnet block in a bank, the placement of each of the galvanometers in the line determining the location of a selectable character in a line on the recording paper, each of said galvanometers having a rotatable mirror mounted on a suspension system within the galvanometer;

a character-generating element interposed in the optical path between the galvanometer mirrors and the recording paper, the element defining a selection of alpha-numeric characters to be printed, the selection of characters in the element being arranged in an aligned side by side relationship;

means connected to each galvanometer for producing deflection of the mirrors from a rest position to a predetermined position relative to the light source and the character to be printed by that galvanometer; and

means for pulsing the light source responsive to the deflection of the mirrors whereby light from the source images and records all of the selected characters on the paper simultaneously with each pulsing of the light source.

7. An apparatus according to claim 6 wherein the character-generating element is a mask having a plurality of translucent characters located therein.

8. An apparatus according to claim 6 wherein the character-generating element is a support having a plurality of reflective characters located thereon.

9. An apparatus for recording characters and symbols comprising:

-a photosensitive recording medium;

a light source;

a plurality of DArsonval galvanometers, each of the plurality of galvanometers supporting a mirror for reflecting light from the source in a predetermined direction toward the recording medium;

a magnet block adapted for mounting the plurality of galvanometers in a side by side relationship, the placement of each galvanometer intermediate the ends of the magnet block determining the location of a character on the recording medium intermediate the sides thereof;

a first optical system for collecting and reflecting light from the source to the galvanometer mirrors;

a character-generating element including a plurality of reflectors defining a selection of characters and symbols available for recordation, the element being located in the optical system between the galvanometers and the recording medium with the characters and symbols defined therein being arranged in a linear side by side relationship;

means connected to each galvanometer for producing deflection of the mirrors from a rest position to a predetermined position relative to the light source and the character to be recorded by that galvanometer;

a second optical system interposed between the plurality of galvanometers and the character generating element and between the element and the recording medium; and

means for pulsing the light source responsive to deflection of the various galvanometers whereby all of the characters comprising the line of information to be recorded are recorded simultaneously on the medium in accordance with the deflections of each of the plurality of galvanometers.

10. A high-speed alpha-numeric printer comprising:

a character-generating element defining a plurality of alpha-numeric characters arranged in a line;

a photosensitive recording medium on which the characters are to be recorded located at one end of an optical system, the medium having a capacity of at least two characters per line;

a bank of galvanometer-mounted mirrors located at the opposite end of the optical system, the number of galvanometers in the bank corresponding to the line capacity of characters of the medium;

a light source located intermediate the ends of the optical system and at an angle to a line of sight path between the galvanometer mirrors and the recording medium;

a first optical system for directing and focussing light from the source onto the bank of galvanometer mirrors; and

a second folded optical system interposed in the path between the :galvanometer mirrors and the recording medium, the optical system comprising a first lens system between the mirrors and the charactergenerating element and a second spherical lens system interposed in the path between the charactergenerating element and the recording medium whereby light reflected by the mirrors images the element characters on the photosensitive medium.

References Cited UNITED STATES PATENTS 2,600,168 6/1952 Klyce 954.5 2,900,884 8/ 1959 Coleman 95-4.5 3,024,079 3/ 1962 Salvatori 346-409 3,064,545 11/1962 Scantlin 954.S 3,224,349 12/ 1965 Schumann 95-45 40 JOHN M. HORAN, Primary Examiner. 

1. AN APPARATUS FOR RECORDING CHARACTERS AND SYMBOLS COMPRISING A PHOTOSENSITIVE RECORDING MEDIUM, A LIGHT SOURCE, A PLURALITY OF D''ARSONVAL GALVANOMETERS, EACH OF THE PLURALITY OF GALVANOMETERS SUPPORTING A MIRROR FOR REFLECTING LIGHT FROM THE SOURCE IN A PREDETERMINED DIRECTION, AND OPTICAL SYSTEM FOR COLLECTING AND REFLECTING LIGHT FROM THE SOURCE TO THE GALVANOMETERS, A CHARACTER-GENERATING ELEMENT INCLUDING A PLURALITY OF TRANSLUCENT APERTURES DEFINING THE CHARACTERS AND SYMBOLS TO BE RECORDED, MEANS CONNECTED TO EACH GALVANOMETER FOR PRODUCING DEFLECTION OF THE MIRRORS FROM A REST POSITION AND AN OPTICAL SYSTEM INTERPOSED BETWEEN THE PLURALITY OF GALVANOMETERS AND THE ELEMENT AND BETWEEN THE ELEMENT AND THE MEDIUM FOR IMAGING THE CHARACTERS TO BE RECORDED ON THE MEDIUM IN ACCORDANCE WITH THE DEFLECTIONS OF EACH OF THE PLURALITY OF GALVANOMETERS. 